Flash Flood Warning 4, NWS Flagstaff, AZ

514 
WGUS75 KFGZ 120945
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
245 AM MST THU JUL 12 2018

AZC005-121115-
/O.CON.KFGZ.FF.W.0004.000000T0000Z-180712T1115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino-
245 AM MST THU JUL 12 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 415 AM MST FOR
COCONINO COUNTY...

At 200 AM MST, a stream gauge in Supai reported a rapid rise to 19.7 
feet with flood stage at 17 feet. Flash flooding is ongoing. Heavy 
rain has ended with only light rain expected through 4 AM MST.

Some locations that will experience flooding include...
Supai and Havasupai Reservation. 

This includes the following streams and drainages...Pasture Wash...
Little Coyote Canyon...Havasu Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now. Act quickly to protect your life.

At a stream level of 17 feet...minor flooding will occur. Foot
bridges will be washed out in Supai Campground. Some campsites will
be flooded. Campers may be stranded in portions of the campground.

&&

LAT...LON 3628 11280 3630 11279 3630 11277 3633 11275
      3632 11273 3632 11272 3634 11273 3635 11271
      3610 11257 3612 11283

$$
JJ

523 
WGUS75 KFGZ 121117
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
417 AM MST THU JUL 12 2018

AZC005-121126-
/O.EXP.KFGZ.FF.W.0004.000000T0000Z-180712T1115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Coconino-
417 AM MST THU JUL 12 2018

...THE FLASH FLOOD WARNING FOR COCONINO COUNTY HAS EXPIRED...

Flood waters have receded along Havasu Creek in the Supai area. 
Flooding is no longer expected to pose a threat. 

LAT...LON 3628 11280 3630 11279 3630 11277 3633 11275
      3632 11273 3632 11272 3634 11273 3635 11271
      3610 11257 3612 11283

$$
JJ

Area Forecast Discussion
National Weather Service Flagstaff AZ
850 PM MST Wed Jul 11 2018

.SYNOPSIS...The monsoon weather pattern will persist over Arizona
through the coming weekend, with daily rounds of showers and
thunderstorms.

&&

.UPDATE...
Minor changes to the forecast to take into account current
satellite, radar, and ground observations. Short term models
continue to show precipitation continuing into the overnight
hours.

Will let the current flash flood watch stand due to the
very rainfall rate efficient environment. Slow moving storms,
continue to develop and work their way across the area. Cloud top
temperatures are generally beginning to decrease across the area,
however the strongest storms currently located in Southern
Yavapai county continue to find areas that have not seen
significant storm activity so far to day and continue to have
vigorous updrafts as noted by the cold overshooting tops detected
by IR channels. These stronger storms will continue to threaten
flash flood prone areas, and overnight products may become
necessary.

As storm activity decreases overnight, cloud cover should remain
in place through the morning hours that could impact initiation
timing for the onset of tomorrows convection. Despite the possible
delay to initiation, another active monsoon day is anticipated.

&&

.PREV DISCUSSION /216 PM MST/... A very moist monsoonal surge
continues to move into the area today. Precipitable water amounts
from this mornings upper air soundings show nearly an inch of
precipitable water in Flagstaff with amounts approaching 2 inches
down in the Phoenix area. Additional moisture is forecast to move
into the area creating even more efficient heavy rain producing
storms this afternoon and evening.

An interesting wrinkle in today's forecast is the development and
movement of a mesoscale convective vortex associated with an
overnight mesoscale convective complex in Sonora, Mexico.

This additional source of vorticity aloft could help promote
storm growth later today as it moves through the lower elevation
deserts to the south.

Because of the aforementioned potential, a flash flood watch is
in effect through late this evening for Yavapai County and
Northern Gila county because of the enhanced threat of flash
flooding. Areas of particular concern include water recreation
areas across Yavapai and Gila counties, along with low water
crossings and fire scars in the watch area.

Further north along the rim widespread convection is already
ongoing with slow moving storms producing significant amounts of
rain. Thankfully these storms remain relatively small, pulse
storms. This type of storm formation is helping mitigate flash
flood potential due to the small area of impact and short lived
nature of these storms currently forming on the high country.

Generally speaking storm motion will continue to be light and to
the northwest, with a more northerly push expected as the evening
goes on.

Continuing Thursday through early next week...Monsoon moisture
will remain across Arizona with medium to high grade monsoon
activity will continue each day.

&&

.AVIATION...For the 06Z package...Mostly VFR conditions and
light variable winds across northern Arizona. Areas of MVFR/IFR
conditions will occur near areas of rain showers and thunderstorms.
Expect areas of slow moving showers and thunderstorms first
developing over higher terrain after 16Z, becoming widespread
during the afternoon and decreasing after 03Z. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous afternoon and evening showers
and thunderstorms will continue through the forecast period. Daytime
relative humidity values ranging from 25 to 45 percent, with good
overnight recovery from 80 to 100 percent. Expect generally light
winds, except near storms or associated with outflows.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch until 2 AM MST Thursday FOR AZZ008-018-037.

&&

PUBLIC...Suk
AVIATION...DB
FIRE WEATHER...Suk

For Northern Arizona weather information visit
weather.gov/flagstaff